"I consider the incident unacceptable, and we cannot ignore it, because the protection of Russian business interests has long been and is likely to remain a national priority," Sergei Ivanov told a session of the government commission for industry, technology and transport development.
A team of over 50 security officers raided the Kremenchug oil refinery, operated by Ukrtatnafta, a Russian-Ukrainian joint venture, to reinstate former board chairman Pavel Ovcharenko, dismissed in 2004.
Ivanov said the incident, already denounced by authorities in Tatarstan and the Russian government, had also dealt "an obvious and considerable blow to relations between Russian investors and their Ukrainian counterparts."
The Kremlin expressed on Tuesday its concern about Ukraine's inaction over the incident, with Kiev pledging to settle the conflict as soon as possible.
Tatar oil company Tatneft, which supplies 80% of oil to the Kremenchug oil refinery, was forced to stop oil deliveries following the raid.
The oil refinery has a capacity of 6 million metric tons (44 million bbl), but only a mere 4 million metric tons (29.4 million bbl) has been delivered there since early this year.
The latest reports quoted Rostislav Vakhitov, head of the Tatar trade mission in Ukraine, as saying that the raid was carried out by Privat, a Ukrainian business group.
"I am not saying that the raid was performed by Kolomoisky [a Privat co-owner], an entire conglomerate of interests is involved there. Others, quite powerful in Ukraine, who have certain influence in Russia, are also behind it," Vakhitov said without specifying their names.
Privat has not yet made any comment on the report.
Vakhitov also accused Ukraine's Fuel and Energy Minister Yuriy Boiko of playing a role in the conflict. "The man did everything to make the problem surrounding Ukrtatnafta a frightful mess," Vakhitov said.
The official blamed Boiko for generating a dispute over an 18.3% stake in the oil refinery, "an indisputable share made disputable."
Ukrtatnafta was established at the Kremenchug oil refinery in 1994. Two foreign companies, AmRuz and Sea Group, close to Tatneft management, bought an 18.3% stake in 1999. Ukraine attempted to reestablish control of the stake, but the country's Supreme Court ruled in May 2006 that AmRuz and Sea Group were legitimate shareholders.
However, Ukrtatnafta's registrar transferred the 18.3% stake from ING Bank Ukraine, a shareholder representing Tatar shareholders' interests, to Ukraine's state-owned oil and gas company Naftogaz, which now controls a 61.3% stake in Ukrtatnafta. Tatar shareholders protested the move.
The Tatar ministry of property and land resources now controls 28.8% in Ukrtatnafta.
Ukrtatnafta is expected to discuss the situation at a shareholder meeting set for November 15.